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About This Project
I’ve always been partial to oil-based polyurethane varnish. The depth and slight ambering bring out the beauty of wood grain like a natural oil finish, but with two important distinctions—it’s harder and is very resistant to stains and moisture.
You can also use waterborne urethane finishes with great results, but the color and depth you get are no match for oil-based urethanes. If you choose a waterborne product, the process for achieving a smooth finish is basically the same. Just be sure you use a tack cloth that’s appropriate for waterborne finishes, such as cheesecloth moistened with denatured alcohol.
Getting a smooth, blemish-free finish with oil-based polyurethane is within your grasp if you follow the steps in this article. And no, you don’t have to spray on the finish to get great results. A good-quality natural-bristle brush, a reasonably dust-free, well-ventilated space and some patience are all you need.
Your Finish Will Only Be as Smooth as Your
Wood
The first step to a good finish is a smooth surface. Sand
your project with progressively finer grits of sandpaper. Paper with a higher
grit number removes the deeper scratches left by paper with a lower-numbered
grit. Most projects need an initial sanding with medium sandpaper (100-grit)
followed by a fine paper (150-grit) and then an extra-fine sanding with
220-grit.
Carefully examine the surface. Look closely for any scratches left by coarse-grit sandpaper. Once the wood is blemish free, remove the dust. I use a shop vacuum with a soft brush attachment, followed by a wipe-down with a lint-free cloth moistened with mineral spirits. Finally, to be completely sure the surface is free of dust, wipe it with a tack cloth.
A Clean Finishing Room Is a
Must
A friend of mine, known for nice work but rough finishes,
does his finish work in his dusty shop. Don’t make the same mistake.
Create a finishing room, or at least thoroughly clean your shop or garage of
sawdust before you start.
You must have good ventilation as well. Work with open windows. Have an exhaust fan facing out through a window to remove vapors and crack a window at the other end of the room to let fresh air in. If you’re sensitive to fumes or can’t get good ventilation, it’s a good idea to wear a respirator with an organic cartridge. A fan placed near the workpiece is bad news and will only blow dust right on your project. The idea here is a gentle flow of air in and then out.
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